Extreme upper level cyclonic vorticity events in relation to the Southern Hemisphere jet stream
Extreme upper level cyclonic vorticity events in relation to the Southern Hemisphere jet stream
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与南半球急流相关的极端高层气旋涡度事件
DOI：
10.1002/2014gl060009
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发表时间：
2014
影响因子：
5.2
通讯作者：
N. Harnik
中科院分区：
文献类型：
--
作者：
N. Harnik
本文研究了南半球极端高层气旋性涡度事件发生频率的平均季节变化及其与急流的关系。在南半球夏季至秋季，高空急流核心最常出现极端气旋性涡度，而在南半球冬季至春季，副热带急流的极向侧翼出现一个主峰，涡动驱动急流的极向侧翼出现一个次峰。合成分析表明，在这两个季节的极端与波破碎和细长涡舌的形成。在夏季，极端事件发生时，波传播的涡驱动急流非线性中断，而在冬季，极端事件发生时，涡驱动急流上的波与副热带急流上的波相互作用。在这两个季节，这些极端高层涡度事件与显着的正降水异常和交替的正负表面温度异常的模式。
The mean seasonal variation in the frequency of occurrence of extreme upper level cyclonic vorticity events, and its relation to the jet stream, is examined in the Southern Hemisphere. During the austral summer to fall, extreme cyclonic vorticity occurs most frequently at the upper level jet stream core, while during the austral winter to spring, there is a main peak on the poleward flank of the subtropical jet and a secondary peak on the poleward flank of the eddy‐driven jet. Composite analysis shows that the extremes in both seasons are associated with wave breaking and the formation of elongated vorticity tongues. In summer, extreme events occur when waves propagating on the eddy‐driven jet break nonlinearly, while in winter, extreme events occur when waves on the eddy‐driven jet interact with waves on the subtropical jet. In both seasons, these extreme upper level vorticity events are associated with significant positive precipitation anomalies and a pattern of alternating positive and negative surface temperature anomalies.
影响因子：
3.1
作者：
P. Berrisford;B. Hoskins;E. Tyrlis
通讯作者：
P. Berrisford;B. Hoskins;E. Tyrlis